Field
The present invention relates to a method of discharging water from a fuel cell and a fuel cell system.
Related Art
In a polymer electrolyte fuel cell, hereinafter simply referred to as “fuel cell”, a large amount of water is produced as a result of a power generation reaction. In some cases, a scavenging processing with using scavenging gas is executed while an operation of the fuel cell is temporarily stopped or terminated, to reduce the water remaining in the system, as disclosed by JP2008-053086A for example.
In the technique disclosed in the JP2008-053086A, to facilitate discharging of water from the fuel cell system in a mobile object, a scavenging flow rate and a scavenging time are changed in accordance with an inclination angle of the mobile object. However, the inventor of the present application has found out that the configuration of simply changing the scavenging flow rate and the scavenging time in accordance with the inclination angle of the mobile object might cause the following problem.
For example, in a fuel cell system installed in a mobile object, exhaust gas from the fuel cell is separated into a gas component and a liquid component by a gas-liquid separator. In this configuration, the gas component is circulated to the fuel cell by a circulation pump, and the liquid component is temporarily stored in the gas-liquid separator and is then discharged as exhaust water. When the scavenging with a high scavenging flow rate is started in the fuel cell system by increasing the rotational speed of the circulation pump while the mobile object is inclined, the water stored in the gas-liquid separator might be sucked up by the circulation pump.
As described above, in some pipe configurations of the fuel cell system, the configuration of simply changing the scavenging flow rate and the scavenging time in accordance with the inclination angle of the mobile object might end up in hindering the discharging of water. Furthermore, the scavenging might cause problems such as increase in noise and consumed energy. All things considered, there is still a room for improvement in the technique of discharging the water from the fuel cell through the scavenging processing.